Art of electoplating



2 Sheets-Sheet 1 a QM? ATTORNEYS July 14, 1925.

E. A. COADY ET AL ART 0F ELEGTROPLATING Filed DBC. 11, 1924 .AJ/ulyL414,` 1925. l

E. A. COADY ET AL ART OF ELECTROPLATING 2 Sheets-Sheet 2 Filed Deo. 11,1924 mm i lu 1 ATTORNEYS Patented duly 14, 1925.

aren vSTATES 1,545,941 PATENT oFFlcs.'

EDWARD A. COADY, F NEW YORK, AND FREDERIC W. OLMSTEAD, Oli" HEMPSTEAD,NEW YORK, ASSIGNORS. BY MESNE'ASSIGNMENTS, T0 FREDERICK CONLIN, OF

WESTFIELD, NEW JERSEY.

.ART 0F ELECTROPLATING.

Application led December 11, 1924. Serial No. 755,144.

T0 ZZ whom, it may concer/n.: Be it known that We, EDWARD A. CoADY c.and FREDERIC lV. OLMSTE'AD, citizens of the United States, andresidents, respectively, of New York, county of New York, and State ofNew York, and Hempstead, county of Nassau, and State of New York, haveinvented certain new andi useful Improve'- ments in the Art ofElectroplating; and we do hereby declare. the following to be a full,clear, and eXact'description of the invention, such as will enableothers skilled inthe art to which it appertains to make and` use thesame.

rIhis invention relates to an imp-roved brush for electrolyticallyapplying metals, such as'nickel, to conducting surfaces. It haspreviously been proposed to apply nickel icoatings or plat-ings toconducting surfaces 2O by means of a brush withv an anode arranged sothat electrolysis takes vplaces in the brush. The present invention.relates more particularly to improvements in. the construction of thebrush employed in such operations; and this invention provides animproved brush which is easily handled,

which enables an expeditious and eflicientA application of such metalliccoatings, 'which enables the application of vmetallic coatings 5o ofgood physical quality and of good lapypea-rance, and which has otherimportant advantages which will appear from the folloi-ving descrip-tionand illustration., .Y

In a brush for this .purpose described in: an application of FrederickConlin nliled January 12, 1925, Serial No. 1831 the anode is arrangedwithin the bristle head of the brush so as to be wholly immersed inplating solution retained by theV bristles of the 40 brush. The anode isthus submerged in plating solution when. the brush is in -use so `thatthe maximum area of the anode is eX- posed and so that a moreuniformdistribution of the flow of current throu h the electrolyte retained inthe brush 1s promoted. Uniformity of distribution of the plating currentassists in producing a metallic deposit of good physical properties andavoids burning of the metallic coatingdue to eX- cessive currentdensityvover localized areas.

In the improved brush of the present invention, the anode is similarlyarranged to be wholly immersed in plating solution retained by thebristles of the brush, and a substantially rigid apron is arranged aboutthe brush bristles so as to prevent any contact of the anode in thebrush with the surface being plated while nevertheless allowing freemovement of the brush bristles.

There no protection is provided to prevent contact between the anode andthe surface` being plated, the flexing ofthe brush bristles may exposethe anode which may thus b e contacted with the surface being plated.Such contact results in short-circuit causing excessive current flow andtending to mar thesurface by burning.` The physical contact of the anodealso may .mar the surfalce being plated. By providing a substantiallyrigid apron about the brush bristles in the improved lbfrush of thep-resent invention, however, such contact 1s prevented withoutsacrificing free movement of the brush bristles or the ease of applyingthe brush yin .the plating operation.

This apron is advantageously flared outwardly away from the bristles ofthe brushj toward the applied end of the bristles to allow them to movefreely within the ap-ron.

The apron need not completely enclose thev anode 'within the brush. Thebristles, as arranged in a body in the brush, have a maximum angle offieXure beyond which no ordinary pressure applied in using the brushwill bend them. In the improved brush of the present invention,advantage is takenol" this maximum angle of iexure'bfy arrangthe brushmay frequently be accompaniedby the liberation of gas.- The movement ofthe bristles of the brush over the anode immersed therein largelyprevents polarization, but, where the gasv liberated is confined 1nthebrush, a somewhat-similar result may becaused mechanically bydisplacement of the electrolyte about the anode by. the-gas -liberatedand confined inthe brush. 'This within the bristle head of the brush andso as causes overheating, reduces the capacity of y P'Ihe provision ofgas relieving means is particularly advantageous where an otherwise 'gastight apron'is employed, 4but certain ad- F' l tratflad' vantages areobtained by the provision of gas relieving means -in brushes withoutaprons.

he invention will be further described in connection with theaccompanying drawings which show several brushes embodying theinvention, but it will be understood that this yfurther description andillustration are for the purpose of exempliication and that theinvention is not limited thereto. In the accompanying drawings: t Fig.1-represents, in section, a flat brush embodying the invention, on line1-1 of Fig. 2,

2 is a side View of the brushl illusin Fig. 1, Fig. 3 isa fragmentaryview showing a. somewhat modified type of brush head,

Fig. 4' represents, partly in section, a modified type of brushembodying the invention, f .v Fig. 5 represents, partly in section, acircular-brush embodying the invention, and Fig. 6 is a section on line6 6 of Fig. 5,. r The brush illustrated in Figs. 1 and 2 is made up of aseparable brush head'7 and a handle 8. The brush bristles 9 aresuitably4 vsecured vin the `brush head 7. The handle 8- vmay be .ofha'rd rubber or other suitable insulating and impervious material andthe brush head 7 may also be of insulating material suzh as hard rubber.The bristles may be set in rubber in the head'as indicated at 10 in thedrawing. lThe head 7 is provided with an apron 11 extending downwardlyabout the bristles 9 and flaring outwardly therefrom. The flare of theapron .advantageously corresponds to the natural curve of the brushbristles when in use, and the lower edge of the apron is rounded off toavoid undue wear of the bristles.- This .comprising lthe bristlesettling and the apron are integral, as illustrated in Figs,v

` such gas does not tend to ldisplace the elec- 1 and'2.

' A holev12 isprovided through the brush head in -alignment with acorresponding 'hole 13 extending through the handle. An

anode 14 is supported within the bristles 9 by means -of a shank 15extending up. wardly through the holes in the brush head' and handle.The edges of the anode are suitably beveled or rounded to avoid unduewear of the bristles. The upper endI of the l shank'lv is threaded andis arranged t0 en" gage an-adjusting nut 1,6 and a lock nut 17, theadjusting nut 16 cooperating with a co1- for v which the exposed end ofthe bristles are applied in the plating operation while4 at vthe sametime allowing full and free\movement of the bristles. As in the brushillustrated` in Fig. 1, this result may be accomplished withoutextending the apron downwardly far enou h to completely enclose theanode but a lig ter and shorter apron may be emf ployed. As will beapparent by reference to Fig. 1, before the anode 14 cancontact with a.surface being plated it must protrude through the brush bristles. Thebrush bristles, however, loffer a certain resistance to lexure whichgradually increases as they are bent and which, with a body of bristlesas in the brush illustrated becomes so great at an angle of maximumde'xure that no ordinary. pressurewill further displace the bristles.With ordinary brush construction, this angle of maximum {iexure amountsto about 27 to 3Q? from the surface to which the brush is applied.Accordingly, in the improved brush of the present invention, the edge 20of the apron 11 isA arranged so vthat no straight line from it to theadjacent the line A--B and the axis of the brush is advantageously e ualto or greater than about 63 but nee not be90.

The apron, 11, in the brush illustrated in Figs. 1 and 2, is providedwith a series ot1| apertures 22A adjacent the handle -end or ixed end ofthel brush bristles and just below the bristle setting 10. A vent 23 isalso provided in the upper end of the handle communicating with theholes 12 and 13 brush. In other words, the angle betweenYA through thebrush head andthe handle.

Any gas liberated by the electrolysis taking place within the brush whenlit is in use is thus provided with means for escape so'that faces orwhere it is applied to the underside or horizontal surfaces. In vsuchinstances, with the shank a extending through the brush head and thehandle, the electrolyte may tend to'leak along the shank through= thehandle. To prevent this, a packing 24v is provided in the joint betweenthe handle 8a and the brush head 7. A series of Vents are arranged inthe apron on the brush head to allow for theescape of any gas formedduring the electrolysis, and, to 1nh1b1t any leakage of electrolytethrough these vents,

they are arranged in a part of the apron which is normally held in closecontact lwith the brush bristles so that the brush bristles Iact toretain the solution While permitting the escape of gas through theapertures.

The brush illustrated in Fig. 4 is ofthe same'general construction asthe brush illustrated in Fig. l except in the shape of the apron, in theabsenceof gas vents, and in the provision of packing about the shanksupporting the anode. This type of brush is particularly adapted formore or less continuous use in plating surfaces from the underside.Packin 24b is provided in the joint between the rush head 7l and thehandle 8b to prevent leakage of the electrolyte along the -shank l5bsupporting the anode. The apron 11b, instead of closely contacting i iththe' bristles 9" just below the bristle setting and then graduallyflaring outwardly, is cup shaped to provide .a free space about thebristles from the bristle setting toward the free end of the bristles.In use, the brush is dipped in the plating solution and inverted, thecup shaped apron 1lb serving to hold excess platinar solution and toprevent dripping from the brush bristles. vIn the inverted position, anygas formed escapes toward the free end of the bristles. While a brush ofthis construction In the round brush illustrated in Figs. 5y

and 6, the anode 26 is in the form of a round rod arranged within thebrush bristles 9 and'integral with the shank 15. Instead -of beingintegral with the brush head 7, the apron llc is separable therefrom.With vsome electrolytes, and where the brush is used but infrequently,the provision of a. separable apron may be desirable to facilitatecleaning of the brush. The anode and the supporting -shank'extendthrough the brush head and the brush handle 8c to the adjustablesupporting means on the up-per end of the handle as in the brushillustrated in Fig. l.

In using the improved brush ofthe present porting shank, and thenegative pole of the current source is connected to the conductingsurface. to be plated. The brush is then saturated with a suitableelectrolyte, as by 'dipping in the electrolyte solution, and is' appliedto the surface to be plated. The plating solution is electrolyzed in thebrush and the metal is deposited at the point of contact between thebrush bristles and the conductingsurfaee. Thermovement of the brushbristlcs'ovcr the conducting surface to be plated, the cathode, promoteseffectivel depolarization at the cathode, so that the plating operationproceeds smoothly and uniformly. The distance between the end of`thepanode and the end of the brush bristles is adjusted to promoteuniform distribution of current flow through the electrolyte retained bythe brush without unduly increasing the resistance through the brush.

In ,using the brush of the present invention for nickel plating, forexample, an electrolyte containing 281 gms. of crystallized nickelsulfate (NiSO4-6I-I2O), 8 gms. of sodium fluoride, 30 gms. boric acid,and 2 gms. of glucose per litre may be used at ordinary temperature witha potential be- `tween the anode in the brush and the conducting surfaceto be plated of about 20 to 50 voltsor somewhat less. The brush isadvantageously -connected in series with a resistance large enouglrtorender the variation vin resistance in the brush when in use immaterial.For example, the brush may be connected to a. volt power line through aresistance of from about 25 to 40 ohmsA or more. For nickel plating, theanode is advantageously made of nickel so that. vit. will replace thenickel content of the electrolyte in the brush as the metal is platedtherefrom. The shank supporting the anode may also be of nickel, or ofsome material 'l' substantially insoluble in the electrolyte such aslead, orcf some material lower in the electromotive series than nickeland which will not plate out of the solution such as iron.

Advantageously, the anode isv adjusted so that it does not come nearerto the surface to be plated than about the thickness of bristles aroundthe anode. For example, in the brushes illustrated, the anode may bearranged about l from the end of the'bristles when the brush is freefrom contact with the surface to be plated; It is also advantageous toarrange the anode so that it has a surface exposed to the electrolyte inthe brush equal to or greater than the area of contact between the brushand the surface to be plated when the brush is in use. (laissentdensities isr-v bath practice may be employed-and a con-i sequentincrease in the rate of deposition obtained without sacrifice of thequality or appearance of the metallic plating. Before application of theplating with the brush, the surface to be plated may be cleaned andvpolished in any of the well-known ways.

We cla-im:

' 1. An improved brush for electroplating conducting surfaces,'whichcomprises a brisvtle head and 'an anode arranged with and surrounded bythe bristles, an electrical connection to the anode, and a substantiallyrigid apron arranged about the bristles.

2. An improved brush for electroplating conducting surfaces,which'comprises a brisv less than 90 but not less than about with theaxis of the brush.

3; vAn improved brush for electroplating tle head andan anode, arrangedwithin the bristles, an electrical connectionto the anode,

vand a substantially rigid apron arranged about the bristles, the lowerledge of the apron and the lower edge of the anode being arranged sothat all sraight lines through adjacent points thereof make an angle of63 conducting surfaces, which comprises a bristle head and an. anodearranged within and surrounded by the bristles, an electrical connectionto thel anode, and :a substantially rigid apron arranged about thebristles, and flaring outwardly therefrom toward the apy plied end ofthe bristles.

' a substantially rigid apron arranged-about the bristles toward theirfree end, and aperthe bristles in close contact with-the bristles towardtheir fixed end and flaring away from tures through the apron-.where itis in close Contact with the bristles.

6. An improved brush for electro-plating conducting surfaces, whichcomprises a bristle head and a handle, an anode arranged Within .thebristles and supported on a shank extending through the handle, means onthe handle for adjusting the position of the lanode along theaxis of thebrush, an electrical connection to the anode, and a substantiallyrigidapron arranged about the bristles.

7. An improved brush for electroplating conducting surfaces, whichcomprises a bristle head and a handle, an anode arranged Within thebristles and supported on a shank extending through a hole in thebristle head and handle, means for relieving gas through the said hole,an electrical connection'to the anode, and a substantially rigid apronar.

ranged about the bristles.

8. An improved brush for electroplating conducting surfaces, whichcomprises a bristle head and a handle, an anode arranged within thebristles and supported on a shank extending through a holel in thebristle head and handle, the hole being large enough to provide a freespace. about the shank, an electrical connection to the anode, and avent for relieving gas from the handle end of the said hole.

9. An improved brush for tle head and an anode arranged within thebristles, an electrical connection to the anode and means for relievinggas from the space in the bristles about the anode.

1 l0. An improved brush for electroplating conducting surfaces, whichcomprises abristle head and an anode within the bristles, an imperviousapron 'arranged about the bristles, an electrical connection to theanode, and -means for relieving` gas from the space inthe brush Withinthe apron.

In testimony whereof we aiiix our signa-' tures. l i.

EDWARD A. ooAn'Y. vaanname W. onMsTEAD.

electroplating -conducting surfaces, which comprises a bris-

